define(['THREE'], function (THREE) {

    /**
     * WebGL port of Subpixel Morphological Antialiasing (SMAA) v2.8
     * Preset: SMAA 1x Medium (with color edge detection)
     * https://github.com/iryoku/smaa/releases/tag/v2.8
     */

    var SMAAEdgesShader = {

        defines: {

            "SMAA_THRESHOLD": "0.1"

        },

        uniforms: {

            "tDiffuse": {value: null},
            "resolution": {value: new THREE.Vector2(1 / 1024, 1 / 512)}

        },

        vertexShader: [

            "uniform vec2 resolution;",

            "varying vec2 vUv;",
            "varying vec4 vOffset[ 3 ];",

            "void SMAAEdgeDetectionVS( vec2 texcoord ) {",
            "	vOffset[ 0 ] = texcoord.xyxy + resolution.xyxy * vec4( -1.0, 0.0, 0.0,  1.0 );", // WebGL port note: Changed sign in W component
            "	vOffset[ 1 ] = texcoord.xyxy + resolution.xyxy * vec4(  1.0, 0.0, 0.0, -1.0 );", // WebGL port note: Changed sign in W component
            "	vOffset[ 2 ] = texcoord.xyxy + resolution.xyxy * vec4( -2.0, 0.0, 0.0,  2.0 );", // WebGL port note: Changed sign in W component
            "}",

            "void main() {",

            "	vUv = uv;",

            "	SMAAEdgeDetectionVS( vUv );",

            "	gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );",

            "}"

        ].join("\n"),

        fragmentShader: [

            "uniform sampler2D tDiffuse;",

            "varying vec2 vUv;",
            "varying vec4 vOffset[ 3 ];",

            "vec4 SMAAColorEdgeDetectionPS( vec2 texcoord, vec4 offset[3], sampler2D colorTex ) {",
            "	vec2 threshold = vec2( SMAA_THRESHOLD, SMAA_THRESHOLD );",

            // Calculate color deltas:
            "	vec4 delta;",
            "	vec3 C = texture2D( colorTex, texcoord ).rgb;",

            "	vec3 Cleft = texture2D( colorTex, offset[0].xy ).rgb;",
            "	vec3 t = abs( C - Cleft );",
            "	delta.x = max( max( t.r, t.g ), t.b );",

            "	vec3 Ctop = texture2D( colorTex, offset[0].zw ).rgb;",
            "	t = abs( C - Ctop );",
            "	delta.y = max( max( t.r, t.g ), t.b );",

            // We do the usual threshold:
            "	vec2 edges = step( threshold, delta.xy );",

            // Then discard if there is no edge:
            "	if ( dot( edges, vec2( 1.0, 1.0 ) ) == 0.0 )",
            "		discard;",

            // Calculate right and bottom deltas:
            "	vec3 Cright = texture2D( colorTex, offset[1].xy ).rgb;",
            "	t = abs( C - Cright );",
            "	delta.z = max( max( t.r, t.g ), t.b );",

            "	vec3 Cbottom  = texture2D( colorTex, offset[1].zw ).rgb;",
            "	t = abs( C - Cbottom );",
            "	delta.w = max( max( t.r, t.g ), t.b );",

            // Calculate the maximum delta in the direct neighborhood:
            "	float maxDelta = max( max( max( delta.x, delta.y ), delta.z ), delta.w );",

            // Calculate left-left and top-top deltas:
            "	vec3 Cleftleft  = texture2D( colorTex, offset[2].xy ).rgb;",
            "	t = abs( C - Cleftleft );",
            "	delta.z = max( max( t.r, t.g ), t.b );",

            "	vec3 Ctoptop = texture2D( colorTex, offset[2].zw ).rgb;",
            "	t = abs( C - Ctoptop );",
            "	delta.w = max( max( t.r, t.g ), t.b );",

            // Calculate the final maximum delta:
            "	maxDelta = max( max( maxDelta, delta.z ), delta.w );",

            // Local contrast adaptation in action:
            "	edges.xy *= step( 0.5 * maxDelta, delta.xy );",

            "	return vec4( edges, 0.0, 0.0 );",
            "}",

            "void main() {",

            "	gl_FragColor = SMAAColorEdgeDetectionPS( vUv, vOffset, tDiffuse );",

            "}"

        ].join("\n")

    };

    /*
     *
        #if defined(SMAA_PRESET_LOW)
        #define SMAA_THRESHOLD 0.15
        #define SMAA_MAX_SEARCH_STEPS 4
        #define SMAA_DISABLE_DIAG_DETECTION
        #define SMAA_DISABLE_CORNER_DETECTION
        #elif defined(SMAA_PRESET_MEDIUM)
        #define SMAA_THRESHOLD 0.1
        #define SMAA_MAX_SEARCH_STEPS 8
        #define SMAA_DISABLE_DIAG_DETECTION
        #define SMAA_DISABLE_CORNER_DETECTION
        #elif defined(SMAA_PRESET_HIGH)
        #define SMAA_THRESHOLD 0.1
        #define SMAA_MAX_SEARCH_STEPS 16
        #define SMAA_MAX_SEARCH_STEPS_DIAG 8
        #define SMAA_CORNER_ROUNDING 25
        #elif defined(SMAA_PRESET_ULTRA)
        #define SMAA_THRESHOLD 0.05
        #define SMAA_MAX_SEARCH_STEPS 32
        #define SMAA_MAX_SEARCH_STEPS_DIAG 16
        #define SMAA_CORNER_ROUNDING 25
        #endif
     */
    var SMAAWeightsShader = {

        defines: {

            "SMAA_MAX_SEARCH_STEPS": "8",
            "SMAA_AREATEX_MAX_DISTANCE": "16",
            "SMAA_AREATEX_PIXEL_SIZE": "( 1.0 / vec2( 160.0, 560.0 ) )",
            "SMAA_AREATEX_SUBTEX_SIZE": "( 1.0 / 7.0 )"

        },

        uniforms: {

            "tDiffuse": {value: null},
            "tArea": {value: null},
            "tSearch": {value: null},
            "resolution": {value: new THREE.Vector2(1 / 1024, 1 / 512)}

        },

        vertexShader: [

            "uniform vec2 resolution;",

            "varying vec2 vUv;",
            "varying vec4 vOffset[ 3 ];",
            "varying vec2 vPixcoord;",

            "void SMAABlendingWeightCalculationVS( vec2 texcoord ) {",
            "	vPixcoord = texcoord / resolution;",

            // We will use these offsets for the searches later on (see @PSEUDO_GATHER4):
            "	vOffset[ 0 ] = texcoord.xyxy + resolution.xyxy * vec4( -0.25, 0.125, 1.25, 0.125 );", // WebGL port note: Changed sign in Y and W components
            "	vOffset[ 1 ] = texcoord.xyxy + resolution.xyxy * vec4( -0.125, 0.25, -0.125, -1.25 );", // WebGL port note: Changed sign in Y and W components

            // And these for the searches, they indicate the ends of the loops:
            "	vOffset[ 2 ] = vec4( vOffset[ 0 ].xz, vOffset[ 1 ].yw ) + vec4( -2.0, 2.0, -2.0, 2.0 ) * resolution.xxyy * float( SMAA_MAX_SEARCH_STEPS );",

            "}",

            "void main() {",

            "	vUv = uv;",

            "	SMAABlendingWeightCalculationVS( vUv );",

            "	gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );",

            "}"

        ].join("\n"),

        fragmentShader: [

            "#define SMAASampleLevelZeroOffset( tex, coord, offset ) texture2D( tex, coord + float( offset ) * resolution, 0.0 )",

            "uniform sampler2D tDiffuse;",
            "uniform sampler2D tArea;",
            "uniform sampler2D tSearch;",
            "uniform vec2 resolution;",

            "varying vec2 vUv;",
            "varying vec4 vOffset[3];",
            "varying vec2 vPixcoord;",

            "#if __VERSION__ == 100",
            "vec2 round( vec2 x ) {",
            "	return sign( x ) * floor( abs( x ) + 0.5 );",
            "}",
            "#endif",

            "float SMAASearchLength( sampler2D searchTex, vec2 e, float bias, float scale ) {",
            // Not required if searchTex accesses are set to point:
            // float2 SEARCH_TEX_PIXEL_SIZE = 1.0 / float2(66.0, 33.0);
            // e = float2(bias, 0.0) + 0.5 * SEARCH_TEX_PIXEL_SIZE +
            //     e * float2(scale, 1.0) * float2(64.0, 32.0) * SEARCH_TEX_PIXEL_SIZE;
            "	e.r = bias + e.r * scale;",
            "	return 255.0 * texture2D( searchTex, e, 0.0 ).r;",
            "}",

            "float SMAASearchXLeft( sampler2D edgesTex, sampler2D searchTex, vec2 texcoord, float end ) {",
            /**
             * @PSEUDO_GATHER4
             * This texcoord has been offset by (-0.25, -0.125) in the vertex shader to
             * sample between edge, thus fetching four edges in a row.
             * Sampling with different offsets in each direction allows to disambiguate
             * which edges are active from the four fetched ones.
             */
            "	vec2 e = vec2( 0.0, 1.0 );",

            "	for ( int i = 0; i < SMAA_MAX_SEARCH_STEPS; i ++ ) {", // WebGL port note: Changed while to for
            "		e = texture2D( edgesTex, texcoord, 0.0 ).rg;",
            "		texcoord -= vec2( 2.0, 0.0 ) * resolution;",
            "		if ( ! ( texcoord.x > end && e.g > 0.8281 && e.r == 0.0 ) ) break;",
            "	}",

            // We correct the previous (-0.25, -0.125) offset we applied:
            "	texcoord.x += 0.25 * resolution.x;",

            // The searches are bias by 1, so adjust the coords accordingly:
            "	texcoord.x += resolution.x;",

            // Disambiguate the length added by the last step:
            "	texcoord.x += 2.0 * resolution.x;", // Undo last step
            "	texcoord.x -= resolution.x * SMAASearchLength(searchTex, e, 0.0, 0.5);",

            "	return texcoord.x;",
            "}",

            "float SMAASearchXRight( sampler2D edgesTex, sampler2D searchTex, vec2 texcoord, float end ) {",
            "	vec2 e = vec2( 0.0, 1.0 );",

            "	for ( int i = 0; i < SMAA_MAX_SEARCH_STEPS; i ++ ) {", // WebGL port note: Changed while to for
            "		e = texture2D( edgesTex, texcoord, 0.0 ).rg;",
            "		texcoord += vec2( 2.0, 0.0 ) * resolution;",
            "		if ( ! ( texcoord.x < end && e.g > 0.8281 && e.r == 0.0 ) ) break;",
            "	}",

            "	texcoord.x -= 0.25 * resolution.x;",
            "	texcoord.x -= resolution.x;",
            "	texcoord.x -= 2.0 * resolution.x;",
            "	texcoord.x += resolution.x * SMAASearchLength( searchTex, e, 0.5, 0.5 );",

            "	return texcoord.x;",
            "}",

            "float SMAASearchYUp( sampler2D edgesTex, sampler2D searchTex, vec2 texcoord, float end ) {",
            "	vec2 e = vec2( 1.0, 0.0 );",

            "	for ( int i = 0; i < SMAA_MAX_SEARCH_STEPS; i ++ ) {", // WebGL port note: Changed while to for
            "		e = texture2D( edgesTex, texcoord, 0.0 ).rg;",
            "		texcoord += vec2( 0.0, 2.0 ) * resolution;", // WebGL port note: Changed sign
            "		if ( ! ( texcoord.y > end && e.r > 0.8281 && e.g == 0.0 ) ) break;",
            "	}",

            "	texcoord.y -= 0.25 * resolution.y;", // WebGL port note: Changed sign
            "	texcoord.y -= resolution.y;", // WebGL port note: Changed sign
            "	texcoord.y -= 2.0 * resolution.y;", // WebGL port note: Changed sign
            "	texcoord.y += resolution.y * SMAASearchLength( searchTex, e.gr, 0.0, 0.5 );", // WebGL port note: Changed sign

            "	return texcoord.y;",
            "}",

            "float SMAASearchYDown( sampler2D edgesTex, sampler2D searchTex, vec2 texcoord, float end ) {",
            "	vec2 e = vec2( 1.0, 0.0 );",

            "	for ( int i = 0; i < SMAA_MAX_SEARCH_STEPS; i ++ ) {", // WebGL port note: Changed while to for
            "		e = texture2D( edgesTex, texcoord, 0.0 ).rg;",
            "		texcoord -= vec2( 0.0, 2.0 ) * resolution;", // WebGL port note: Changed sign
            "		if ( ! ( texcoord.y < end && e.r > 0.8281 && e.g == 0.0 ) ) break;",
            "	}",

            "	texcoord.y += 0.25 * resolution.y;", // WebGL port note: Changed sign
            "	texcoord.y += resolution.y;", // WebGL port note: Changed sign
            "	texcoord.y += 2.0 * resolution.y;", // WebGL port note: Changed sign
            "	texcoord.y -= resolution.y * SMAASearchLength( searchTex, e.gr, 0.5, 0.5 );", // WebGL port note: Changed sign

            "	return texcoord.y;",
            "}",

            "vec2 SMAAArea( sampler2D areaTex, vec2 dist, float e1, float e2, float offset ) {",
            // Rounding prevents precision errors of bilinear filtering:
            "	vec2 texcoord = float( SMAA_AREATEX_MAX_DISTANCE ) * round( 4.0 * vec2( e1, e2 ) ) + dist;",

            // We do a scale and bias for mapping to texel space:
            "	texcoord = SMAA_AREATEX_PIXEL_SIZE * texcoord + ( 0.5 * SMAA_AREATEX_PIXEL_SIZE );",

            // Move to proper place, according to the subpixel offset:
            "	texcoord.y += SMAA_AREATEX_SUBTEX_SIZE * offset;",

            "	return texture2D( areaTex, texcoord, 0.0 ).rg;",
            "}",

            "vec4 SMAABlendingWeightCalculationPS( vec2 texcoord, vec2 pixcoord, vec4 offset[ 3 ], sampler2D edgesTex, sampler2D areaTex, sampler2D searchTex, ivec4 subsampleIndices ) {",
            "	vec4 weights = vec4( 0.0, 0.0, 0.0, 0.0 );",

            "	vec2 e = texture2D( edgesTex, texcoord ).rg;",

            "	if ( e.g > 0.0 ) {", // Edge at north
            "		vec2 d;",

            // Find the distance to the left:
            "		vec2 coords;",
            "		coords.x = SMAASearchXLeft( edgesTex, searchTex, offset[ 0 ].xy, offset[ 2 ].x );",
            "		coords.y = offset[ 1 ].y;", // offset[1].y = texcoord.y - 0.25 * resolution.y (@CROSSING_OFFSET)
            "		d.x = coords.x;",

            // Now fetch the left crossing edges, two at a time using bilinear
            // filtering. Sampling at -0.25 (see @CROSSING_OFFSET) enables to
            // discern what value each edge has:
            "		float e1 = texture2D( edgesTex, coords, 0.0 ).r;",

            // Find the distance to the right:
            "		coords.x = SMAASearchXRight( edgesTex, searchTex, offset[ 0 ].zw, offset[ 2 ].y );",
            "		d.y = coords.x;",

            // We want the distances to be in pixel units (doing this here allow to
            // better interleave arithmetic and memory accesses):
            "		d = d / resolution.x - pixcoord.x;",

            // SMAAArea below needs a sqrt, as the areas texture is compressed
            // quadratically:
            "		vec2 sqrt_d = sqrt( abs( d ) );",

            // Fetch the right crossing edges:
            "		coords.y -= 1.0 * resolution.y;", // WebGL port note: Added
            "		float e2 = SMAASampleLevelZeroOffset( edgesTex, coords, ivec2( 1, 0 ) ).r;",

            // Ok, we know how this pattern looks like, now it is time for getting
            // the actual area:
            "		weights.rg = SMAAArea( areaTex, sqrt_d, e1, e2, float( subsampleIndices.y ) );",
            "	}",

            "	if ( e.r > 0.0 ) {", // Edge at west
            "		vec2 d;",

            // Find the distance to the top:
            "		vec2 coords;",

            "		coords.y = SMAASearchYUp( edgesTex, searchTex, offset[ 1 ].xy, offset[ 2 ].z );",
            "		coords.x = offset[ 0 ].x;", // offset[1].x = texcoord.x - 0.25 * resolution.x;
            "		d.x = coords.y;",

            // Fetch the top crossing edges:
            "		float e1 = texture2D( edgesTex, coords, 0.0 ).g;",

            // Find the distance to the bottom:
            "		coords.y = SMAASearchYDown( edgesTex, searchTex, offset[ 1 ].zw, offset[ 2 ].w );",
            "		d.y = coords.y;",

            // We want the distances to be in pixel units:
            "		d = d / resolution.y - pixcoord.y;",

            // SMAAArea below needs a sqrt, as the areas texture is compressed
            // quadratically:
            "		vec2 sqrt_d = sqrt( abs( d ) );",

            // Fetch the bottom crossing edges:
            "		coords.y -= 1.0 * resolution.y;", // WebGL port note: Added
            "		float e2 = SMAASampleLevelZeroOffset( edgesTex, coords, ivec2( 0, 1 ) ).g;",

            // Get the area for this direction:
            "		weights.ba = SMAAArea( areaTex, sqrt_d, e1, e2, float( subsampleIndices.x ) );",
            "	}",

            "	return weights;",
            "}",

            "void main() {",

            "	gl_FragColor = SMAABlendingWeightCalculationPS( vUv, vPixcoord, vOffset, tDiffuse, tArea, tSearch, ivec4( 0.0 ) );",

            "}"

        ].join("\n")

    };

    var SMAABlendShader = {

        uniforms: {

            "tDiffuse": {value: null},
            "tColor": {value: null},
            "resolution": {value: new THREE.Vector2(1 / 1024, 1 / 512)}

        },

        vertexShader: [

            "uniform vec2 resolution;",

            "varying vec2 vUv;",
            "varying vec4 vOffset[ 2 ];",

            "void SMAANeighborhoodBlendingVS( vec2 texcoord ) {",
            "	vOffset[ 0 ] = texcoord.xyxy + resolution.xyxy * vec4( -1.0, 0.0, 0.0, 1.0 );", // WebGL port note: Changed sign in W component
            "	vOffset[ 1 ] = texcoord.xyxy + resolution.xyxy * vec4( 1.0, 0.0, 0.0, -1.0 );", // WebGL port note: Changed sign in W component
            "}",

            "void main() {",

            "	vUv = uv;",

            "	SMAANeighborhoodBlendingVS( vUv );",

            "	gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );",

            "}"

        ].join("\n"),

        fragmentShader: [

            "uniform sampler2D tDiffuse;",
            "uniform sampler2D tColor;",
            "uniform vec2 resolution;",

            "varying vec2 vUv;",
            "varying vec4 vOffset[ 2 ];",

            "vec4 SMAANeighborhoodBlendingPS( vec2 texcoord, vec4 offset[ 2 ], sampler2D colorTex, sampler2D blendTex ) {",
            // Fetch the blending weights for current pixel:
            "	vec4 a;",
            "	a.xz = texture2D( blendTex, texcoord ).xz;",
            "	a.y = texture2D( blendTex, offset[ 1 ].zw ).g;",
            "	a.w = texture2D( blendTex, offset[ 1 ].xy ).a;",

            // Is there any blending weight with a value greater than 0.0?
            "	if ( dot(a, vec4( 1.0, 1.0, 1.0, 1.0 )) < 1e-5 ) {",
            "		return texture2D( colorTex, texcoord, 0.0 );",
            "	} else {",
            // Up to 4 lines can be crossing a pixel (one through each edge). We
            // favor blending by choosing the line with the maximum weight for each
            // direction:
            "		vec2 offset;",
            "		offset.x = a.a > a.b ? a.a : -a.b;", // left vs. right
            "		offset.y = a.g > a.r ? -a.g : a.r;", // top vs. bottom // WebGL port note: Changed signs

            // Then we go in the direction that has the maximum weight:
            "		if ( abs( offset.x ) > abs( offset.y )) {", // horizontal vs. vertical
            "			offset.y = 0.0;",
            "		} else {",
            "			offset.x = 0.0;",
            "		}",

            // Fetch the opposite color and lerp by hand:
            "		vec4 C = texture2D( colorTex, texcoord, 0.0 );",
            "		texcoord += sign( offset ) * resolution;",
            "		vec4 Cop = texture2D( colorTex, texcoord, 0.0 );",
            "		float s = abs( offset.x ) > abs( offset.y ) ? abs( offset.x ) : abs( offset.y );",

            // WebGL port note: Added gamma correction
            "		C.xyz = pow(C.xyz, vec3(2.2));",
            "		Cop.xyz = pow(Cop.xyz, vec3(2.2));",
            "		vec4 mixed = mix(C, Cop, s);",
            "		mixed.xyz = pow(mixed.xyz, vec3(1.0 / 2.2));",

            "		return mixed;",
            "	}",
            "}",

            "void main() {",

            "	gl_FragColor = SMAANeighborhoodBlendingPS( vUv, vOffset, tColor, tDiffuse );",

            "}"

        ].join("\n")

    };

    return {SMAAEdgesShader: SMAAEdgesShader, SMAAWeightsShader: SMAAWeightsShader, SMAABlendShader: SMAABlendShader};
});